In certain industrial areas, e.g., in mining or when entering closed spaces, the persons working there must carry oxygen self-rescuers with them in order to be able to escape from the area in case of an unbreathable atmosphere. These oxygen self-rescuers make it possible for the user to build up a breathing circuit, which operates independently from the ambient air, in a short time. The tidal volume must be collected for this in a breathing bag and carbon dioxide breathed out during each breath is bound chemically and oxygen taken up by the body is again introduced into the air. This is achieved with potassium dioxide (KO2) in most oxygen self-rescuers of various manufacturers. KO2 reacts with the moisture present in the expired air and in the released gaseous oxygen in the process. In addition, potassium hydroxide, which is an effective binder for carbon dioxide (CO2) and reacts with the carbon dioxide to form potassium carbonate, is formed in the above-mentioned reaction.
To learn how to put on an oxygen self-rescuer in exercises, there is a “training device” for each model of oxygen self-rescuer. This training device contains all the functional parts that are necessary for the training, but no functional breathing air regenerating cartridges. This is not meaningful for cost reasons and because of the disposal, which becomes necessary. For simplicity's sake, the expired air is replaced with ambient air during each breath in training devices.
The trainees sometimes complain that they do not achieve any training effect in respect to the occurring airway resistance, the dryness of the regeneration air and the temperature that becomes established during breathing with real devices.
A self-rescuer training device, in which a granular filling consisting of ceramic bodies is provided in a container, through which the breathing air flows, is known from DE 19 42 806 U. A heating coil for heating the breathing air is arranged within the filling of ceramic bodies, which is used to store heat. The wall of the container is provided with an aluminum-lined asbestos layer on the inner side and the outer side for heat insulation against the environment.
A thermal switch, which interrupts the power supply in the form of a two-point controller when a predetermined temperature limit is exceeded, is used for the temperature control of the heating coil. The prior-art training device is suitable for possible applications only conditionally, because auxiliary electric power is necessary for operating the heating coil.